Zeppelin Disappointments, Airship Woes

Serendipitously, Maggie Koerth-Baker, the brilliant science editor for Boing Boing, recently wrote about her visit to the zeppelin Eureka, just on the heels of my own posts here and at Txchnologist about airships. She offers an independent confirmation that as appealing and inspiring as these vehicles may be, they suffer from practical drawbacks that help to explain why our skies are not festooned with them.

As she writes, Maggie had been looking forward to a ride on the Eureka, which is a new technology zeppelin that carries 12 passengers and two crew, primarily for tourism but also sometimes for research jobs that need a hovering platform. The Eureka sounds like a marvelous little craft (I use “little” advisedly as an endearment, because it is longer than a 747), and Maggie’s enthusiasm for airships shines. She comes to recognize, however, that their comparatively large size, low speed, ballast and ground support requirements, and susceptibility to wind, among other considerations, do make them less practical than airplanes for most aviation jobs, as I had discussed.

It’s worth emphasizing that the Eureka is a form of zeppelin, and not one of the hybrid air vehicles on which I had focused. Those more advanced designs do have features that would give them a big edge over craft like the Eureka: they are faster, more stable on the ground, and so on. Many of the basic problems relative to airplanes still apply, however, despite the ingenuity of the hybrid makers in making the most of their vehicles’ performance.

For example, consider the susceptibility of airships to wind. Maggie quotes one of the crew as explaining, “An airship is like a big sail” about an acre in area:

That “sail” means landings, loadings, and takeoffs are tricky on windy days. On a landing, Belanger said, the wind could catch the zeppelin and push it sideways, like a beach ball skittering across the ground. The wind also moves the ship while it’s tethered down. The Eureka is 246 feet long. Not coincidentally, that’s also the radius of the mooring circle that the ship forms as wind slowly pushes it around on it’s little back wheel. All of that meant that the Eureka had to sit on the ground while planes were safely taking off and landing on the runway behind her.

The situation for hybrids is somewhat different. Because their fuselages are flatter and wider, they don’t present proportionally quite as much surface area to the wind and they aren’t lighter than air, so they can be more stable while moored. But they do still get pushed.

Of course, strong crosswinds angling onto a runway can keep airplanes grounded, too. As a representative of Hybrid Air Vehicles Ltd. explained to me, crosswinds don’t represent the same kind of problem for hybrids during takeoffs and landings: they can simply pivot and take off or land with the wind at their backs no matter which way it is blowing. That’s not a bad strength for hybrids to have.

But it seems to me that it comes at a cost. One of the claimed advantages for hybrids is that their static lift (innate buoyancy) helps them gain altitude quickly during takeoffs, so they need only very short cleared spaces as runways—perhaps just a couple of times their length. That could be a big plus in places where clearing land and building a tarmac could be difficult or expensive. But for a hybrid as long as a football field to be able to fly off in any direction, it then needs to start off in the middle of a cleared circle with a radius of at least 200 or 300 meters—conservatively, 12.5 hectares (31 acres). That may not erase the difference in cost between clearing a space for an airship and building a simple runway for planes, but it has to narrow it. Or you can confine the airships to a smaller, narrower landing space, at the cost of eliminating the crosswind advantage.

In the end, Maggie seems to draw much the same conclusion that I did about why airships are a lovely but rather marginal form of transport:

Ultimately, I came away from my visit two a zeppelin with two thoughts. First, it’s a nice reminder that the world is pretty complicated, and it got to be the way it is for many reasons. Sure, the Hindenburg contributed to busting the zeppelins’ bubble. But improved airplane engineering probably played a bigger role.

13 Responses to Zeppelin Disappointments, Airship Woes

Bravo! Exactly.
One of the reasons why Turtle Airships are designed to land, primarily, in water.

Generaly, a given water surface for airship operations is large and unobstructed; a harbor, lake, even mid-ocean. Taking on large amounts of water as ballast immediately upon landing, the Turtle Airship becomes as “heavy” and as stable as a boat.

Not quite a fair representation of airships in the Eureka, though. She overlooks one crucial fact: The Eureka is relatively tiny. She’s a minuscule(again, by comparison) sightseeing Zeppelin, and obviously is NOT designed to be competitive with other aircraft on their respective turf. Airships cannot be accurately sized by anything less than their volume, because of the Square-Cube law they so take advantage of. Eureka, for instance, is a paltry 240 feet long and 8,225 cubic meters, compared to Graf Zeppelin, which was 777 feet long and 105,000 cubic meters. But at those sizes, the square-cube law kicks it up to eleven: the Hindenburg was only 30 feet longer than Graf Zeppelin in any direction, but had a volume of 200,000 cubic meters. So, essentially, it was almost 25 times as large, and this was in 1936, mind.

I don’t blame her, though. It’s easy to use the Eureka as an evaluation of all airships, it’s just not very accurate, is all.

And the landing space is small potatoes of a problem compared to the benefit of being able to purchase a 200-ton lifter for $92mil(HAV 606 and being able to operate it for less than a $136mil Airbus cargo plane capable of carrying 20-30 tons. At that vast gulf in payload and price, speed diminishes rapidly as an issue.

I might be reassured more by your argument if it was one that the people building the new airships believed. In my interviews, they readily acknowledged that none of them foresaw competing with traditional cargo freight except in special situations (as in serving remote areas of Manitoba) where speed wasn’t an issue and building a road/rail infrastructure seemed out of the question. I haven’t seen any analysis of the prospects for airships that concludes otherwise, in fact (if you know of one, please let me know). Those jobs will exist, so I’m certainly not arguing that airships won’t have anything to do, but I don’t see good reason to doubt my conclusion (and Maggie’s, it seems) that for most transport jobs worth doing by air, airplanes and helicopters probably are better choices.

The purchase and operation costs for hybrid airships you cited are still speculative. HAV hasn’t built a 606. HAV is working with Northrop Grumman to build Long Endurance Multi Intelligence Vehicles for military surveillance that would have lifting configurations for on the order of 20 tons, if I’m remembering right, and that contract is for three vehicles at a cost of more than $500 million. That cost wouldn’t reflect commercial production costs but it does give me reason to question whether a vehicle with 10 times that capacity will cost just $92 million.

Hi folks,
John has not considered that the LEMV has state of the art surveillance and remote control systems, so the cost of each vehicle does not relate to the cost of a larger HAV once it is in mass production. The bigger HAV’s are not much more expensive than the smaller ones, because the expensive electronics and control systems are the same. In mass production they would be cheaper than equivalent payload fixed wing aircraft.
Helicopters are a no go, because they use far too much fuel, do not have the range and require a lot of serious maintenance downtime. Also when a helicopter suffers an incident the results tend to be of a very permanent nature.
Regards JB (www.hybridairship.net)

Hi folks,
I think the author misses the big advantage of hybrid air vehicles and that is that there is no need for an airport. The clear space includes water or snow and there is rather a big difference between the cost of building an all weather airport and the cost of clearing a landing site good enough for a hoverskirt undercart to cross. Also HAV’s can do vertical lift and drop operations, or heavy lift at a reduced payload or long range.
If you are in need of a Helium sniffing laugh then try my Gasbags site: http://www.hybridblimp.net or easy to remember: http://www.airship.me for the worlds only lighter than air comedy web site.
Regards JB (Airship & Blimp Consultant http://www.hybridairship.net )

@John Rennie
Correct again, helicopters and planes ARE in fact better in MOST cargo applications that require air transport, because they’re moving things over relatively short distances and at a relatively small scale. They transport small things, like mail or parts that do not require 200 tons of lifting capacity. There’s simply no need for something of the scale of an airship in most instances. But there ARE air cargo applications where the cargo planes, such as a Hercules or Galaxy, are simply being used for lugging as much weight as possible from point A to B. For firefighting, an airship would be a mind-boggling game-changer. Right now, seaplanes and helicopters(!!) are being used to fight fires instead! And there’s tye surveillance application that so many airships are gunning for right now where their benefits are staggering. Humanitarian airships, with their vastly superior capacity, could serve as airborne hospitals or simply deposit food vastly more cheaply and effectively. Lastly, there’s the sky liner angle to consider. A flying cruise ship would hold great appeal to many people. Airships trounce other methods soundly on those fronts. Yes, it is theoretical at this point, but I see no reason to doubt the performance projections considering the records held by ordinary airships like Snowbird, from decades or even nearly a century ago.

Lastly, the LEMV project does indeed cost $500 mil, but that’s because they are starting nearly from scratch here, not just for the airships, but for the surveillance systems as well. Planes have development and infrastructure on their side. The LEMV’s production infrastructure and their spy payloads have to be built and tested as well as the vehicles themselves. Hundreds of new staff have to be hired and trained. They may be using off-the-shelf technology wherever they can, but they just don’t have the preexisting infrastructure that planes have. Once they do, and start mass-production of models, costs will go way down. And remember, although the HAV 606 has ten times the capacity, that does not mean it’s ten times as expensive, because it’s only twice as large. Square-cube law, remember?

The idea of compressing the lifting gas, hydrogen, helium or methane, within the airship (proposed hybrid) to reduce the lift requires cooling the gas in to a liquid form. The molecules of the lifting gas are too small to be compressed using a membrane because the gas molecules would just pass through the membrane. Lifting gas bleeding through gas cells or gas balloons has always been an issue.

The practicality of “Hindenburg class” airships, over 7,000,000 cubic feet is for passenger travel just like cruise ships. The only barrier to passenger airships for long distance cruising is vision and money.

Actually, no. Your initial premise is wrong. Buoyant gases- such as Ammonia, Hydrogen, Methane, Helium, Nitrogen, etc. do not require liquidation in order to reduce lift. That’s utter nonsense, with the exception of Ammonia as a lift gas, due to the ease of doing just that. But Ammonia has only 40% the lift of Hydrogen, and is caustic. It’s been rejected as a lift gas, at least with current technologies.

But I digress. Some actually do propose compression of the lift gas as a means of controlling lift- Aeros has even flown a full-sized airship that has done just that. It is one of their Helium advertizing airships, modified to house the COSH(Control Of Static Heaviness) system as a testbed for their new DARPA hybrid Zeppelin, the PELICAN. The Pelican itself is designed to be able to control lift in all modes of flight, through either compression of the Helium or heating the Helium. This does not require liquefaction for the very simple reason that the gases derive their buoyancy from being slightly less dense than the atmosphere, and all gases are very easily compressible, unlike water. It requires roughly as much pressure as a bicycle tire to completely negate the lift of Helium, for instance. Furthermore, your complaint of the gas “bleeding through” is doubly wrong because it assumes that the membranes are as permeable as elastic balloons, and because they won’t be compressed against the hull or gas cells in the first place. The hull of a modern airship consists of composites of Kevlar, Tedlar, Mylar, Vectran, Nylon, and other coatings. It’s layered and almost completely impermeable; some hulls only lose 3% of their volume PER ANNUM. Secondly, the compression system on the PELICAN- thus far the only one in existence- relies on ballonets within the envelope. Any minute quantities of gas that DOES escape would just escape into the low-pressure hull.

Lastly, before the question even comes up, yes, the storage system is safe. The pressures involved are very slight, the fabrics are unnecessarily strong, and it’s already been demonstrated to work perfectly fine. It’s not going to “pop” the airship. It would just leak faster than a blow to the main hull, and even then it would just leak back into the airship.

An airship doesn’t need any ground space to land. In fact, they never need to touch the ground at all. A mooring tower would be the best way to bring an airship in. Simply send a line over to the crew in the mooring tower and have them winch the beast into place, then have a grand staircase for the passengers to enter and exit from, with a lobby where they can check in and out. The airship can swing all around the tower and never touch the ground. All supplies can be loaded through this same port. You could even make it a multi-story affair where a freight elevator would stop on one floor and all that can be loaded into an elevator that takes it to the cargo decks located low but inside the center of the hull. Passengers would go down the grand staircases or walk to the central elevators and down to their cabins along the lower walls of the hull so everyone has a great view.

The one huge advantage airships have is they are huge. Why not use all that space to allow passengers to have staterooms with window walls. They don’t have to be crammed into a gondola hanging under the hull. With remote cameras and modern process controls, a modern airship could be a very efficient and comfortable way to travel. Like a cruise ship, they would be a moving luxury hotel with great views wherever they go be in over land or sea.

Many people forget that the Empire State Building was built with a mooring tower on top for the big airships of it’s day. People went right to the building. Downtown Manhattan with no cab ride or parking problems.

Well, yes and no. You’re right that for the most part an airship doesn’t strictly need to land. But the concept of just winching one to a mooring tower has significant practical problems of its own, which is why the landing schemes I mentioned are the ones generally discussed by the airship makers themselves. One problem is that if you have to build a big sturdy mooring tower, one with elevators for moving cargo and people up and down and solid enough that it can resist any pulling forces from the airship in a high wind, then you’re committed to a substantial investment at the landing site. But one of the advantages touted for cargolifter airships is that they would be able to put down in remote areas that haven’t had lots of ground prep. So that plan somewhat negates one of the advantages.

Also, having an airship swinging all around the tower as you describe makes it difficult and risky to load and unload cargo and passengers. (How does that grand staircase stay connected securely at both the top and the bottom?) The easy way to solve that problem is to run multiple mooring lines from the airship to ground supports. But if you’re going to use multiple ground supports, then it would be cheaper and easier in most situations simply to bring the airship much closer to the ground and moor it that way, as I described.

The accommodations on luxury passenger airships could indeed be very plush and glamorous, which is why there might be a business awaiting entrepreneurs in that area. As I think I noted in these posts, the criticisms I raised apply primarily to cargo transport, for which the economics and competition are quite different.

Aviation is actually one of those enterprises that requires a sense of vision.
You have to actually convince investors and clients of things that haven’t been done before as lucrative projects.
Airships get there potential from the fact that there isn’t a dominant market structure. Its currently very entrepreneurial and possesses features that are highly desirable for a start-up; such as the exploitation of extremely low fuel costs of operation and lower maintenance.
New materials and advanced powering systems are option that the established industries can’t readily access without competitive development costs.
Dirigibles don’t require the heavy thrusting turbofans like conventional fixed wing craft. It’s even possible to put the equivalent of dirigible parks on an even larger aerostatic platform?
These ideas are not necessarily new, but supporting technical resources are emerging for more competitive markets and securing capital isn’t the major obstacle.
The conventional air travel experience is starting to resemble ‘greyhound’ for most jet travelers. If you can deliver a more relaxing and less expensive way of air travel, airship may be able to deliver into this market base?

The Gleaming Retort — Meet the Author

John Rennie served as editor in chief of Scientific American between 1994 and 2009. Based in New York, he continues to work as a science writer and editor, and as an adjunct instructor in New York University's Science, Health and Environmental Reporting Program. John can be found on Twitter as @tvjrennie.

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